The heart is the center of a person's circulatory system. It includes an electro-mechanical system performing two major pumping functions. The left side of the heart, including the left atrium and left ventricle, draws oxygenated blood from the lungs and pumps it to various organs of the body to provide the organs with oxygen for their metabolic needs. This pumped blood flow is called the cardiac output. The right side of the heart, including the right atrium and right ventricle, draws deoxygenated blood from the organs and pumps it into the lungs where the blood gets oxygenated. The pumping functions are accomplished by contractions of the myocardium (heart muscles). In a normal heart, the sinoatrial node, the heart's natural pacemaker, generates electrical impulses, known as action potentials, that propagate through an electrical conduction system to various regions of the heart to excite myocardial tissues in these regions. Coordinated delays in the propagations of the action potentials in a normal electrical conduction system cause the various regions of the heart to contract in synchrony such that the pumping functions are performed efficiently.
A blocked or otherwise damaged electrical conduction system causes irregular contractions of the myocardium, a condition generally known as arrhythmia. Arrhythmia reduces the heart's pumping efficiency and hence, diminishes the cardiac output. The diminished cardiac output may also be caused by heart failure where the myocardial muscle is weakened and its contractility is reduced. A heart failure patient usually suffers from both a damaged electrical conduction system and a deteriorated myocardium. In response to the reduced cardiac output, the body attempts to adapt in a number of ways that lead to various symptoms as the heart failure condition progresses. The body retains salt and water as a result of reduced urinal output. The salt and water are then accumulated in the lung and/or in peripheral tissues. The water retention may also lead to acute pulmonary edema in which fluid leaks into the air sacs of the lung, causing the patient to gasp for breath. This condition can be fatal if not treated immediately. Another symptom of a patient with heart failure is fatigue on exertion. Once diagnosed with chronic heart failure, the patients is typically managed by interventions such as diet restriction and pharmacologic and/or device therapies. Such interventions keep the patient in a clinically stable state unless punctuated by episodes of acute heart failure decompensation. Acute heart failure decompensation is characterized by fluid overload and shortness or breath, and requires immediate treatment in a hospital or an outpatient clinical setting.
Heart failure has been recognized as a significant public health concern with a huge economic impact. Patients hospitalized with decompensated heart failure reportedly have a high rate of rehospitalization within six months (more then 50% according to some studies), with a significant percentage of them rehospitalized within a month. Hospital readmission is a principal factor responsible for the cost associated with managing heart failure. Premature hospital discharge and insufficient resolution of heart failure worsening are among the factors contributing to the high rate of rehospitalization. Therefore, there is a need to improve management of heart failure hospitalization for reducing the rate of rehospitalization.